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Metasurfaces have recently opened up applications in the quantum regime, including quantum tomography and the generation of quantum entangled states. With their capability to store a vast amount of information by utilizing the various geometric degrees of freedom of nanostructures, metasurfaces are expected to be useful for processing quantum information. Here, we propose and experimentally demonstrate a programmable metasurface capable of performing quantum algorithms using both classical and quantum light with single photons. Our approach encodes multiple programmable quantum algorithms and operations, such as Grover’s search algorithm and the quantum Fourier transform, onto the same metalens array on a metasurface. A spatial light modulator selectively excites different sets of metalenses to carry out the quantum algorithms, while the interference patterns captured by a single-photon camera are used to extract information about the output state at the selected output directions. Our programmable quantum metasurface approach holds promising potential as a cost-effective means of miniaturizing components for quantum computing and information processing.

Two-photon interference is an important effect that is tightly related to the quantum nature of light. Recently, it has been shown that the photon bunching from the Hong–Ou–Mandel (HOM) effect can be used for quantum imaging in which sample properties (reflection/transmission amplitude, phase delay, or polarization) can be characterized at the pixel-by-pixel level. In this work, we perform Jones matrix imaging for an unknown object based on two-photon interference. By using a reference metasurface with panels of known polarization responses in pairwise coincidence measurements, the object’s polarization responses at each pixel can be retrieved from the dependence of the coincidence visibility as a function of the reference polarization. The post-selection of coincidence images with specific reference polarization in our approach eliminates the need in switching the incident polarization and thus parallelized optical measurements for Jones matrix characterization. The parallelization in preparing input states, prevalent in any quantum algorithms, is an advantage of adopting two-photon interference in Jones matrix imaging. We believe our work points to the usage of metasurfaces in biological and medical imaging in the quantum optical regime.

Two-photon interference is an important effect that is tightly related to the quantum nature of light. Recently, it has been shown that the photon bunching from the Hong–Ou–Mandel (HOM) effect can be used for quantum imaging in which sample properties (reflection/transmission amplitude, phase delay, or polarization) can be characterized at the pixel-by-pixel level. In this work, we perform Jones matrix imaging for an unknown object based on two-photon interference. By using a reference metasurface with panels of known polarization responses in pairwise coincidence measurements, the object's polarization responses at each pixel can be retrieved from the dependence of the coincidence visibility as a function of the reference polarization. The post-selection of coincidence images with specific reference polarization in our approach eliminates the need in switching the incident polarization and thus parallelized optical measurements for Jones matrix characterization. The parallelization in preparing input states, prevalent in any quantum algorithms, is an advantage of adopting two-photon interference in Jones matrix imaging. We believe our work points to the usage of metasurfaces in biological and medical imaging in the quantum optical regime. [ABSTRACT FROM AUTHOR]

A highly sensitive, reversible, and linear sensor, exhibiting excellent stability in response to temperature and humidity, has been successfully proposed and demonstrated for the first time. This sensor is achieved by wrapping a polyvinyl alcohol/graphene nanofiber film onto a chiral long-period fiber grating (CLPG), which is fabricated by periodically twisting single mode fiber. In the experiment, the CLPG sensor demonstrates a temperature sensitivity of 74 pm/°C , which is approximately twice as high as that of conventional fiber grating sensors. Note that, by wrapping the graphene nanofiber film on CLPG, the temperature sensitivity of the sensor is up to 115.23 pm/°C in the range of 30°C to 75°C. In addition, CLPG using for humidity sensing is first demonstrated. The humidity sensitivity measures −9.92 pm/%RH with linearity of 0.995 during a change from 40%RH to 80%RH. In comparison to other humidity sensors, the sensitivity of the CLPG is comparable, whereas its sensing linearity stands out notably above the rest. The results show that CLPG has the characteristics of simple fabrication, easy combination with materials, stable performance, and high sensitivity and holds significant development potential in optical fiber sensing application fields. [ABSTRACT FROM AUTHOR]

An optical fiber sensing probe using a composite sensitive film of polyacrylonitrile (PAN) nanofiber membrane and gold nanomembrane is presented for the detection of a carcinoembryonic antigen (CEA), a biomarker associated with colorectal cancer and other diseases. The probe is based on a tilted fiber Bragg grating (TFBG) with a surface plasmon resonance (SPR) gold nanomembrane and a functionalized polyacrylonitrile (PAN) PAN nanofiber coating that selectively binds to CEA molecules. The performance of the probe is evaluated by measuring the spectral shift of the TFBG resonances as a function of CEA concentration in buffer. The probe exhibits a sensitivity of 0.46 dB/(µg/ml), a low limit of detection of 505.4 ng/mL in buffer, and a good selectivity and reproducibility. The proposed probe offers a simple, cost-effective, and a novel method for CEA detection that can be potentially applied for clinical diagnosis and monitoring of CEA-related diseases.